3D Robotics

"Think GPS is cool? IPS will blow your mind."


From Extremetech, a glimpse of a way to do indoor navigation in public spaces:

For all of their awesome applications — from portable navigation devices, to self-driving cars, to cruise missile targeting — the American Global Positioning System and its Russian cohort GLONASS have two fundamental flaws: They don’t work indoors, and they only really operate in two dimensions.

Now, these limitations are fair enough; we’re talking about an extremely weak signal that has traveled 20,200km (12,600mi), after all. Passing through concrete and other solid obstacles is hard enough for a strong, short-range cellular signal — you can’t seriously expect a 50-watt signal traveling 12,000 miles to do the same. Detecting a GPS signal on Earth is comparable to detecting the light from a 25-watt bulb from 10,000 miles.

The situation is a little more complex when it comes to detecting a change in altitude; GPS and GLONASS can measure altitude, but generally the data is inaccurate and too low-resolution (on the order of 10-25 meters) for everyday use. Even with these limitations, though, space-based satellite navigation systems have changed almost every aspect of society, from hardware hacking to farming to cartography to finding a girlfriend.

What if we had a navigation system that worked indoors, though? What if we had an Indoor Positioning System (IPS)? Believe it or not, we’re very nearly already there.

Last year, Google Maps for Android began introducing floor plans of shopping malls, airports, and other large commercial areas. Nokia, too, is working on an indoor positioning system, but using actual 3D models, rather than 2D floor plans. Just last week, Broadcom released a new chip (BCM4752) that supports indoor positioning systems, and which will soon find its way into smartphones.

Unlike GPS and GLONASS, there isn’t a standard way of building an indoor positioning system. Google’s approach tracks you via WiFi — it knows where the WiFi hotspots are in a given building, and through signal strength triangulation it can roughly work out where you are. Nokia’s solution is similar, but it uses Bluetooth instead of WiFi, making it higher resolution (but it would require the installation of lots of Bluetooth “beacons”). Other methods being mooted involve infrared, and even acoustic analysis. None of these approaches are accurate or reliable enough on their own, though — in spaces that are packed with different materials, and roving groups of attenuating meatbags, these signals are simply too noisy.

The Broadcom chip supports IPS through WiFi, Bluetooth, and even NFC. More importantly, though, the chip also ties in with other sensors, such as a phone’s gyroscope, magnetometer, accelerometer, and altimeter. Acting like a glorified pedometer, this Broadcom chip could almost track your movements without wireless network triangulation. It simply has to take note of your entry point (via GPS), and then count your steps (accelerometer), direction (gyroscope), and altitude (altimeter).

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  • Ric: maybe you accidently deactivated GPS with 3G? on my iphone, it does not matter if 3G is activated or not, position accuracy is exactly the same

  • Very cool tech. I'm reminded of the MIT MAV with a hacked Kinect that could generate a 3D models of interior space. I wonder if you could combine that with IPS so that you map the room once, and then all subsequent drones can travel effortlessly.

    Having said that, would anyone really feel physically safe in a confined space where quadcopters are zipping by you? Perhaps they would fly in a dedicated space of the building, flying in formation above our heads, or even via dedicated tunnel systems, and we'd just learn to live with it. We generally become accustomed to potentially dangerous technology when the failure rate is small enough (combustion engines, heavier-than-air craft, nuclear power, etc).

  • Moderator

    Funny, I find exactly the opposite.

    I used my iPhone for a year before setting it up on the phone network. (not as a phone obviously)

    I used only wifi and thought I was getting OK GPS tracks, but once I activated it on a 3G network, the results were alot more accurate.


  • well.. in iphone uses wifi for that

    don't trust me? go into a building, deactivate wifi and search your location, it will ba very weak, now activate wifi -> you will get ~2m precision if there are a few wifi spots around ;)

  • Developer

    For a cheap dedicated indoor tracking system, I would take a look at ultrasound. The system would use the same principle as GPS, and have ultrasound emitters at strategic positions in the building. The emitters would then at fixed intervals, sent out ultrasonic chirps (using a chirp makes it easier to detect and ignore sound reflections from walls etc.) containing relevant information like the emitter position. The receiver could then triangulate it's position by analyzing the time skew of the available emitter chirps.

  • Moderator

    How would an indoor beacon system work?  If you could sync the clocks, could you do gps-style triangulation?

    It seems there would have to be a new non-point to point protocol for this.

    It would be great to set up a few base stations in a room, have them syncronize their clocks, and then have that be the basis for a good precision indoor location system.

    pipe dream?  possible?

  • I think this would be good for setting an initial location, like if you powered up your dronebot inside a building then it could know approximately where it was.  And it could suppliment another location system but it doesn't seem like it has enough accuracy to use alone for navigation or obstacle avoidance.

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